Enhanced cell selection mechanisms in mobile communications

1. A method, comprising: determining, by a processor of a user equipment (UE), a frequency band and a subcarrier spacing (SCS) configuration by checking a profile; performing, by the processor, a cell selection or reselection procedure using the frequency band and the SCS configuration to select a cell of a wireless network; establishing, by the processor, a wireless connection with the selected cell; updating, by the processor, the profile upon either completion of the cell selection or reselection procedure, or receiving information related to one or more SCS configurations in the profile; and maintaining, by the processor, a default SCS configuration among the one or more SCS configurations in the profile, wherein the maintaining of the default SCS configuration comprises: storing a default value for the default SCS configuration in a default value table; and storing a respective exceptional value for each remaining SCS configuration of the one or more SCS configurations as a respective difference relative to the default value, wherein the receiving of the information related to the one or more SCS configurations in the profile comprises either: receiving signaling from the wireless network pertaining to the one or more SCS configurations in the profile; or retrieving the information from a Subscriber Identity Module (SIM) of the UE or a memory of the UE, wherein the updating of the profile comprises: referencing the default value table; and maintaining the default value without change responsive to a value indicated in the information being identical to the default value, and wherein the determining of the SCS configuration corresponding to the frequency band comprises applying the default value responsive to no entry of any SCS configuration in the profile corresponding to the frequency band.

2. The method of claim 1 , wherein the profile is stored in a Subscriber Identity Module (SIM) of the UE, a memory of the UE, or both.

3. The method of claim 2 , wherein the SIM comprises a Universal Subscriber Identity Module (USIM), an embedded SIM (eSIM), an embedded Universal Integrated Circuit Card (eUICC), an integrated SIM (iSIM) or an integrated UICC (iUICC).

4. The method of claim 1 , wherein the profile is received from the network via Radio Resource Control (RRC) signaling, Non-Access Stratum (NAS) signaling, or signaling used in a 3 rd -Generation Partnership Project (3GPP) system.

5. The method of claim 1 , wherein the profile comprises a SCS profile, a Radio Access Technology (RAT) profile, a Public Land Mobile Network (PLMN) profile or a Mobile Country Code (MCC) profile.

6. The method of claim 1 , wherein the profile comprises a SCS profile containing one or more SCS configurations including the SCS configuration, and wherein each of the one or more SCS configurations is associated with respective Public Land Mobile Network (PLMN) information, respective frequency band information, or both.

7. The method of claim 6 , wherein the respective frequency band information is associated with one or more of respective channel bandwidth, a respective resource block, a respective transmission time interval (TTI), and a respective modulation.

8. The method of claim 1 , wherein the profile comprises a SCS profile containing one or more SCS configurations including the SCS configuration, and wherein each of the one or more SCS configurations is associated with a corresponding validity timer representative of a lifetime of a respective SCS configuration of the one or more SCS configurations.

9. The method of claim 1 , wherein the receiving of the signaling comprises receiving Radio Resource Control (RRC) signaling, Non-Access Stratum (NAS) signaling, or signaling used in a 3 rd -Generation Partnership Project (3GPP) system.

10. The method of claim 1 , further comprising: storing, by the processor, a Public Land Mobile Network (PLMN) list in a Subscriber Identity Module (SIM) of the UE, a memory of the UE, or both, wherein the PLMN list contains a plurality of PLMNs that are prioritized, wherein the selecting of the PLMN comprises selecting one of the plurality of PLMNs having a priority higher than that of at least another PLMN of the plurality of PLMNs in the list, and wherein an elementary file (EF) is extended to include one or more SCS configurations in the profile.

11. The method of claim 1 , further comprising: determining the frequency band by a location identification (ID) of a current location of the UE, wherein the location ID comprises a Mobile Country Code (MCC), and wherein the determining of the location ID of the current location of the UE comprises mapping position information of the UE or analyzing system information of the UE.